In the old world a lot of it came down to property ownership. Maybe I owned a wharf, and I collect a fee for every ship that docks. Maybe I owned a warehouse and a merchant paid me a fee to use it. Maybe I owned farmland with tenant farmers paying me for the rights to farm the land.
Honestly it’s a lot of the same stuff as today. The only difference was back in the day it was a lot more of individuals owning stuff rather than businesses owning stuff. There were businesses owning major industry, and that goes back hundreds of years. But it wasn’t really the norm for things to be owned by businesses until about a century ago. These days it would be weird for a wharf to be owned by one guy instead of a business with 50 investors. But that’s how it used to be.
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